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The topics in this unit are: 1 – Hazard symbols 2 – The periodic table 3 – Atomic structure 4 – How many sub-particles? 5 – Electron arrangements 6 – Group 1 elements 7 – Group 1 reactions 8 – Flame tests 9 – Group 7 elements 10 – Displacement reactions 11 – Ions 12 – Ionic compounds 13 – Writing formula Next page

Hazard Symbols Safety precautions are: Wearing gloves and eye protection Washing hands after handling chemicals Using safety screens Work in a fume cupboard Not eating and drinking when working with chemicals Not working near naked flames Main menu Next page corrosive harmful irritant flammable toxic oxidising

The Periodic Table Main menu Next page Periodic Table All the known elements are organised in the Periodic Table groupsperiods It is arranged in columns called groups and rows called periods. number Each group is given a number. similar properties All the elements in the group have similar properties

Atomic Structure Main menu Next page atoms All substances are made of atoms nucleus Atoms have a nucleus in the centre of the atom. protons neutronsElectrons shells The nucleus contains protons and neutrons. Electrons orbit the nucleus in energy shells.Charge Relative mass Proton+11 Electron Neutron01

How many sub-particles? Main menu Next page protonselectrons neutral An atom has the same number of protons and electrons so the electrical charge is neutral overall. number of protons All atoms of the same element have the same element have the same number of protons. protons proton number We can calculate the number of protons by looking at the proton number electrons proton number We calculate the number of electrons by looking at the proton number as the charges need to be equal neutronsmass number minus the proton number We calculate the number of neutrons by the mass number minus the proton number

Electron Arrangements Next page Main menu arranged Electron configurations tell us how electrons are arranged in an atom. rules There are rules to follow when drawing an electron arrangement Work out how many electrons the element has Start filling from the first shell (closest to the nucleus) 1st shell can hold 2 electrons 2 nd shell can hold 8 electrons 3 rd shell can hold 8 electrons

Group 1 Elements Main menu Next page lithium, sodium, potassium, rubidium and caesium. The group 1 elements are lithium, sodium, potassium, rubidium and caesium. alkali metals They are known as the alkali metals. melting and boiling decrease As we move down the group, the melting and boiling points decrease. increases The density increases. increases Reactivity increases

Group 1 Reactions Main menu Next page chlorine metal chlorides Alkali metals react with chlorine to form salts called metal chlorides e.g. 2Na + Cl 2  2NaCl Alkali metals react with oxygen to form metal oxides e.g. 4Na + O 2  2Na 2 O Alkali metals react with water to form metal hydroxides e.g. 4K + H 2 O  2KOH + H 2 In this reaction, the metals float on water melt from the heat and dissolve to form an alkaline solution.

Flame Tests Main menu Next page flame colour The group 1 metals produce a characteristic flame colour when they are heated. Lithium = red Sodium = orange/yellow Potassium = purple line spectrum The light from a flame produces a line spectrum. excited electrons Each line represents excited electrons

Group 7 Elements Main menu Next page fluorine, chlorine, bromine, iodinev The group 7 elements are fluorine, chlorine, bromine, iodinev They exist in pairs - F 2, Cl 2, Br 2, I 2 ElementColourState FluorineYellowGas ChlorineGreenGas BromineOrangeLiquid IodineGreySolid Moving down the group darkerThe colour becomes darker decreasesThe melting point and boiling point decreases

Displacement Reactions Main menu Next page decreases As we move down the group the reactivity decreases displace A more reactive halogen will displace a less reactive halogen 2KI + Cl 2  2KCl + I 2 e.g. 2KI + Cl 2  2KCl + I 2

Ions Main menu Next page charged particles Ions are charged particles neutral charged If atoms gain or lose electrons it is no longer neutral overall. It becomes charged. full outer shell Atoms gain or lose electrons to have a full outer shell. loses positively If the atom loses electrons, the ion is positively charged gains negatively If the atom gains electrons, the ion is negatively charged

Ionic Compounds Next page Main menu ionic bondmetalsnon metals An ionic bond forms between a metals and a non metals. transfer It involves the transfer of electrons from one atom to another Sodium needs to lose one electron Chlorine needs to gain one electron gives The sodium atom gives the electron to the chlorine atom charged Both particles become charged. oppositeattract strong ionic bond The opposite charges attract to form a very strong ionic bond

Writing Formula Next page Main menu chargeformula If we know the charge of an ion, we can work out the formula neutral This is because ionic substances are neutral overall Positive ion Negative ion Formula Na + Cl - NaCl Ca 2+ O 2- CaO Ca 2+ Cl - CaCl 2 equal The charges must be equal to make the substance neutral